Have you guys noticed how Sameer resembles Nanu in mannerisms? I caught up with last two week's episodes over this weekend and distinctly observed in one episode but now I can't remember to provide a clip. It was a scene in school. Sameer was with Munna and Pandit having usual conversation but the way he delivered his dialogue was exactly like Nanu or rather Kiran Kumar the actor.
Sameer and Nanu having similar character traits is expected - given that they are related (obviously) and this is something show writers have kept in mind and same is conveyed to actors and which they enact.
Physical mannerisms are also something that writers can write when they build a character and director can direct accordingly - a trick often used in lost & found movies where characters first notice how similar they are and then the realisation that they are actually related.
It is also possible that younger actors pick acting tips from veterans that they work with both consciously and subconsciously.
It is a very small thing and I don't know what's the reason here, but Randeep/Sameer resembling Nanu/Kiran Kumar is pretty cool. Makes their characters' relationship more authentic and very real.